Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The demand for renewable energy sources has grown out of the humanity’s increasing
need for electricity as well as depleting fossil fuel reserves. Organic-dye sensitised solar cells
were developed as a green, cost-effective alternative to the market-dominating silicon solar
cell technology. The field of photovoltaic devices and organic-DSSCs is interesting because
we want to develop better, more efficient cells at lower costs using environmentally friendly
materials. By studying the fundamental physics and chemistry processes occurring during and
after the interaction of light with these devices, we create a window into the mechanism of
photosynthesis. Our DSSCs were prepared by sensitisation of highly porous ZnO with different
indoline dyes containing the same chromophore, but different alkyl chain lengths bonded
to one of two carboxyl anchors as: DN91 (1 C) < DN216 (5 C) < DN285 (10 C). The role of
the dye molecules is to absorb photons and donate electrons to the ZnO which acts as the
charge acceptor, at the dye|ZnO interface. Through photoelectrochemical characterisation it
was found that the structure of the dyes has an effect on the maximum current (JSC) produced
by the cells: the shorter the alkyl chain, the higher the JSC. This macroscopic investigation
was complimented by microscopic measurements in the form of transient absorption spectroscopy.
This allows us to follow, in real time, the photoinduced oxidation of the dye and
its regeneration occurring through desired and undesired pathways. It was found that the
injection efficiencies of the dye molecules were directly responsible for the trend in the short
circuit currents. / AFRIKAANSE OPSOMMING: Die aanvraag na die ontwikkeling van herwinbare energie bronne spruit voort uit die voorsienbare
uitputting van fossiel brandstof bronne sowel as die groeiende behoefte om aan die
mensdom se elektrisiteit behoeftes te voldoen. Kleurstof gesensitiseerde sonselle is ontwikkel as
’n groen, koste-effektiewe alternatief tot die silikon sonsel tegnologie wat die mark domineer.
Die fotovoltaïse toestel veld, spesifiek organiese kleurstof gesensitiseerde sonselle is interessant
omdat daar ruimte bestaan vir die ontwikkeling van beter meer effektiewe selle in terme van
vervaardigings koste en prosesse wat omgewingsvriendelik is. Deur die fundamentele fisika en
chemiese prosesse wat plaas vind tydens en na lig interaksie met hierdie selle te bestudeer gee
dit insig oor die werkingsmeganisme van fotosintese. Ons kleurstof gesensitiseerde sonselle is
voorberei deur sensitasie van hoogs poreuse ZnO met verskillende indolien kleurstowwe wat
dieselfde kromofoor bevat wat met verskillende alkiel ketting lengtes verbind is aan een van
twee karboksiel ankers as: DN91 (1 C) < DN216 (5 C) < DN285 (10 C). Die rol van die kleurstof
molekules is om fotone te absorbeer en elektrone te doneer aan die ZnO wat as die lading akseptor
dien by die kleurstof|ZnO intervlak. Deur fotoelektrochemiese karakterisasie is bevind
dat die struktuur van die kleurstof ’n effek het op die maksimum stroom (JSC) wat die selle
produseer: hoe korter die die akiel ketting, hoe hoër die JSC. Hierdie makroskopiese ondersoek
is voltooi deur mikroskopiese metings in die vorm van tydopgelosde absorpsiespektroskopie.
Dit laat ons toe om die fotogeinduseerde oksidasie asook regenerasie van die kleurstof te volg
soos wat dit plaas vind deur gewenste sowel as ongewenste roetes. Dit is bevind dat die inspuitings
effektiwiteit van die kleurstof molekules direk verantwoordelik is vir die waarneembare
trajek in die kortsluitings stroom.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/95760 |
| Date | 12 1900 |
| Creators | Minda, Iulia |
| Contributors | Schwoerer, Heinrich, Schlettwein, Derck, Stellenbosch University. Faculty of Science. Dept. of Physics. |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | v, 50 p. |
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